This application for a mid-career investigator award seeks funds to support the PI's research career and mentoring activities. Funds from the award will allow the PI to expand his mentoring activities, develop additional skill sets in longitudinal data analysis and expand his program of research that involves understanding the etiology and longitudinal course of adolescent-onset substance use disorders. This award will result in relief from substantial administrative and clinical responsibilities as the Psychiatric Director of the Addiction, Research and Treatment Services (ARTS), a large treatment program affiliated with the University of Colorado Denver Anschutz Medical Campus. Effort will be redirected toward mentoring activities, career development, and research activities. The PI is currently involved in a number of studies that are examining adolescent and young adult substance use disorders, both from a clinical, behavior genetics, and molecular genetic perspective. The PI will expand his research program by expanding his current research projects to gather more information about adolescent perceptions and patterns of marijuana use in the light of the recent medical marijuana explosion as well as conduct a longitudinal study that will follow a sample of both clinical and community adolescents every 6 months for 3 years to examine the development of marijuana use patterns and associated HIV-risk behaviors.